Within the last decade there has been an ever increasing use of surgical staples, in lieu of conventional sutures, in many internal organ and intestinal procedures from the esophagus to the rectum. U.S. Pat. Nos. 3,193,165; 3,338,847; 3,552,626, 3,593,903 and 3,638,652. together with copending application Ser. No. 890,262, filed Mar. 27, 1978 in the name of Carl T. Becht and entitled INTRALUMENAL ANASTOMOSIS SURGICAL STAPLING INSTRUMENT, teach exemplary types of surgical stapling instruments devised by prior art workers for such procedures. The use of surgical staples and such surgical stapling instruments has made many difficult procedures much simpler. Of even greater importance, however, is the fact that the use of surgical staples significantly reduces the time required for such procedures and therefore reduces the length of time for which the patient must be maintained under anesthetic.
U.S. Pat. Nos. 3,193,165 and 3,388,847 are exemplary of permanent-type, reusable instruments requiring that the staples be hand-loaded into a single ring cartridge. Instruments of this type have several disadvantages. In general, they are complex in structure, expensive to manufacture, bulky and heavy. They must be constantly maintained; disassembled and cleaned after each use; and sterilized for each procedure. Staples must be individually hand-loaded into the cartridge for each procedure. The instrument scalpel must be sharpened periodically and special tools are frequently required for assembly, disassembly, maintenance and replacement of parts.
It is well known that the tubular structures constituting the human alimentary canal, i.e. the esaphogus, small and large intestines, are of varying diameters and wall thicknesses even within the same patient. In order to place a circular anastomosis in the tubular structures of the alimentary canal, instruments of the type described must be introduced into the inner spaced of the organ being sutured. The diameter of the staple containing portion of the instrument must correspond to the internal diameter of the organ being stapled.
The above noted U.S. Pat. No. 3,552,626 teaches interchangeable staple carrying heads of different diameters. Such an instrument, however, not only suffers from those disadvantages mentioned above, but in addition, the interchangeable heads are difficult to install and remove. The minimum size of such heads is limited because of the bulky fittings required for their joinder to the instrument. Furthermore, the instrument is provided with a knurled nose nut which can damage the inside of the intestine during removal of the instrument. The instrument of the above noted copending application can be made wholly disposable or can be a reusable instrument provided with a disposable staple cartridge. As a reusable instrument it would suffer from the drawbacks noted above.
Along with the advantages of the use of surgical staples and surgical stapling instruments, there are certain inherent dangers. First of all, it is necessary to select the proper staple size for the thickness of tissue to be joined. Secondly, even if the proper staple size is selected, the staples must not be formed too tightly or too loosely. If the staples are formed too tightly the blood supply needed for the healing process is cut off and the tissue becomes necrotic. If the staples are formed too loosely, then hemorrhaging and/or leakage can occur. Thus, both too tightly and too loosely formed staples can cause serious problems and complications.
The present invention is directed to an intralumenal anastomosis surgical stapling instrument of extremely simple design. While the instrument may be manufactured in the form of a permanent, reusable instrument, it is particularly adapted to manufacture as a single-use, disposable surgical stapling instrument. The instrument is capable of placing an "end-to-end", "end-to-side", "side-to-side" and "side-to-end" anastomosis. Since the instrument lends itself well to manufacture as a single-use, disposable instrument, it can readily be made in one or more lengths and with staple-containing casings of different diameters to cover most of the internal diameters encountered in the human alimentary canal.
The instrument of the present invention is light weight and easy to manipulate. While the staple-containing casing can mount a single annular array of staples, it preferably contains two staggered annular arrays of staples in concentric pattern eliminating the necessity for over-suturing to stop leakage and bleeding.
The instrument of the present invention is provided with improved gap setting means including means for giving both a visual and a tactile indication that the space between the anvil and the staple-containing casing is within the "working gap" of the instrument and calibrated adjustable vernier means for setting the actual gap, within the "working gap", at a distance appropriate for the thickness of tissues being joined. To this end, the surgical stapling instrument may be used in conjunction with a tissue thickness measuring device of the type, for example, taught in copending application Ser. No. 06/124,955, filed Feb. 26, 1980, in the names of Robert G. Rothfuss and Edwin L. Stith, Jr., and entitled SURGICAL TISSUE THICKNESS MEASURING INSTRUMENT.
The instrument may be provided with a slide safety lockout to prevent accidental ejection of the staples. The instrument may further be vented to equalize pressure on either side of an anastomosis, as will be described hereinafter.
Finally, prior art instruments of the type described have been characterized by the fact that they are difficult to remove from the anastomotic site after the staples are crimped and the tissue is joined. The instrument of the present invention is provided with an improved anvil of unique profile for easy removal of the instrument from the anastomotic site.
Heretofore surgical stapling instruments have been devised with anvil means configured to form the surgical staples into a B-shaped configuration. This is taught, for example, in U.S. Pat. Nos. 3,490,675 and 3,494,533. The anvil of the present invention is provided with anvil pockets so configured as to adequately crimp the surgical staples into a B-shape throughout the range of the "working gap" without requiring the use of staples of different leg lengths.